The corner in question is where West Fayette meets Monroe Street in West Baltimore, the site of one of an estimated 100 open-air drug markets in that beleaguered American city. The year is 1993, a pivotal one in the escalation of Baltimore's illegal round the clock drug trade.

"On every corner, street dealers began using minors, first as runners and look-outs, then as street-level slingers," elaborate David Simon and Ed Burns. "When children became the labour force, the work itself became childlike, and the organisational structure that came with heroin's first wave was a historical footnote."

Anyone who has seen The Wire, Simon and Burns's equally epic and labyrinthine police drama, will be familiar with the crucial role played by children - not just teenagers, but their even younger siblings - in the distribution of heroin and crack cocaine on Baltimore's most notorious corners. Here, those children are made real. Likewise, the dealers, the cops, the hustlers and the politicians: all the venal, murderous, muddle-headed and heroic individuals whose fictionalised alter-egos have so mesmerised viewers on both sides of the Atlantic.

The Corner, which was originally published in the US in 1997, is the book that spawned The Wire. It tracks the lives of several players in Baltimore's drug demi-monde and of some of the hard-working, hard-bitten cops who try in vain to police the corners. It reserves its not inconsiderable anger and scorn for the politicians who, in Wire parlance, "juke the stats" - manipulate the crime figures for personal gain.

Famously, the democratic candidate for mayor of Baltimore, Martin O'Malley, campaigning on an anti-drug ticket, brandished a copy of the book while making a speech on the corner of the title in 1999. Paradoxically, given that the book is, among other things, a fierce polemic against drug prohibition, he won.

Reading The Corner, having watched all five series of The Wire, is an unnerving experience. For once, the drama does not exaggerate the reality. One could say, at the risk of antagonising the show's fanatical fans, that it tends slightly to romanticise it. Look, for instance, at Omar, the cold-hearted but effortlessly cool stick-up artist in The Wire who makes a living by identifying, then robbing at gunpoint, the stash houses of the neighbourhood drug gangs. Onscreen, he is a Hollywood archetype: the cold-blooded outlaw, the loner, the man in black. In real life, as the authors point out, the Omars of Baltimore are living, even by the standards of the gangster "game", on borrowed time, their job "little better than a death wish".

The street lives depicted in The Corner are tougher, sadder and more desperate than those dramatised in The Wire. The first person you meet in the book is Fat Curt, a veteran of the corner, with "needle-scarred hands", arms like "swollen leather" and "bloated legs" who is "bent to this ancient business of survival". He is now caught up in another daily grind, trying to hustle welfare aid for the drug-related lymphoedema that ravages his scarred body. Elsewhere, the young DeAndre is engaged in the struggle to stay straight, often working for a fraction of what he would earn on the corner, while his mother shoplifts to maintain her habit. Then there's Tyreeka, pregnant at 13, feisty and almost proud. What The Corner shows us, often in the graphic detail of hardcore drug use, is that generations have fallen to America's drugs trade.

It is the children, though, who make this such a powerful work. In one of many illuminating passages where first-hand reportage gives way to concise contextualising, Simon and Burns write: "In the 1990s, the drug corner is modelled on nothing more complicated than a fast-food emporium, an environment in which dealing drugs requires about as much talent and finesse as serving burgers... the modern corner has no need for the applied knowledge of previous generations."

The children, more than anyone, know this. They surrender one kind of education for another, the school for the street, the classroom for the corner. They know where their lives are going and what it takes to survive. They see the cost of not surviving all around them. They also, more chillingly, seem drawn to "the game", to its deadly romance and the sense of entitlement, however brief or insecure that may be.

The Corner took more than a year of on-the-street research - what David Simon, who cut his journalistic teeth as a crime reporter on the Baltimore Sun, self-deprecatingly calls "stand-around-and-watch journalism". It is beautifully written, by turns evocative and simmeringly angry. On one level, too, the book is an indictment of contemporary newspaper journalism, where this kind of sustained - and expensive - reportage has been replaced by desk work. In America, it seems, the system has failed several generations of inner-city families and the media have, to a great degree, let the government and the city legislators off the hook.

Early on in The Corner, Simon and Burns point out: "All across the inner city - from Lafayette Courts to Sandown to Cherry Hill - slinging drugs is the rite of passage." In other words, neighbourhoods once considered safe and middle class now have their very own corners. That, perhaps, is the real message of a book that, in the main, avoids messages, that does not preach or proselytise, but simmers with frustration and anger at the great farce that is America's so-called war on crime.